• Journal of Microbiology and Biotechnology
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• 제9권5호
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• pp.637-645
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• 1999

Two putative regulator genes, mocR and mocS, of the moc (mannityl opine catabolism) operons in pTi15955 of the octopine-/mannityl opine-type Agrobacterium tumefaciens strain 15955, were tested for their possible roles as repressors in the moc operons. The regions upstream of macC and mocD, the first structural genes in the two divergently oriented moc operons, were transcriptionally fused into the promoterless lacZ reporter gene. Each of the lacZ-fusions was introduced into Agrobacterium strain UIA5, a Ti plasmid-cured derivative, harboring either a mocR or a mocS clone. The resulting strains were grown in media containing various sugar sources, and the $\beta$-galactosidase activities were quantitatively measured. The results suggested that MocR repressed the expression of macC and macD. The expression of the fused $\beta$-galactosidase was not induced by mannopine (MOP) or possible catabolic intermediates of the opine, e.g. santhopine (SOP), glucose, mannose, or glutamine. However, the repression was significantly relieved by the supplementation of MOP and the concomitant introduction of the agcA gene encoding MOP cyclase that catalyzes the lactonization of MOP to agropine (AGR). These results suggested that AGR, rather than MOP or the other catabolic intermediates, is the inducer for the expression of the operon. On the contrary to previous report showing that the induction levels of macC and macD were lowered by the supplementation of inorganic nitrogen in media, the expression of these genes was not affected by the level of nitrogen in our reporter system. MocS did not strongly repress the expressions of macC and mocD. It is possible that MocS may be involved in the regulation of the operons present downstream of the moc operon, which are responsible for the utilization of mannopinic acid and agropinic acid.

• Molecules and Cells
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• 제25권4호
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• pp.559-565
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• 2008

Members of the TGA family of basic domain/leucine zipper transcription factors regulate defense genes through physical interaction with NON-EXPRESSOR OF PR1 (NPR1). Of the seven TGA family members, TGA4/octopine synthase (ocs)-element-binding factor 4 (OBF4) is the least understood. Here we present evidence for a novel function of OBF4 as a regulator of flowering. We identified CONSTANS (CO), a positive regulator of floral induction, as an OBF4-interacting protein, in a yeast two-hybrid library screen. OBF4 interacts with the B-box region of CO. The abundance of OBF4 mRNA cycles with a 24 h rhythm under both long-day (LD) and short-day (SD) conditions, with significantly higher levels during the night than during the day. Electrophoretic mobility shift assays revealed that OBF4 binds to the promoter of the FLOWERING LOCUS T (FT) gene, a direct target of CO. We also found that, like CO and FT, an OBF4:GUS construct was prominently expressed in the vascular tissues of leaf, indicating that OBF4 can regulate FT expression through the formation of a protein complex with CO. Taken together, our results suggest that OBF4 may act as a link between defense responses and flowering.

• 식물조직배양학회지
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• 제25권3호
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• pp.147-152
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• 1998

AL1-gene은 TGMV의 복제에 매우 중요한 역할을 하고 있다. 이 AL1 gene의 발현을 억제하기 위해서는 식물체내에서 AL1 gene의 antisense RNA의 발현에 의한 억제가 효과적 방법 중에 하나로 알려져 있다. 이런 발현을 식물체내에서 실현시키기 위해 hygromycin 저항성 유전자에 antisense AL1-gene을 연결시키고, 연결된 부위를 CaMV35s-promoter와 octopine synthase gene terminator 사이에 연결시켰다. 이 유전자 발현 단위 부분을 다시 kanamycin 저항성 유전자 발현 단위 부분을 지니고 있는 형질 전환 벡터인 pBinAR에 삽입시켜 새로운 형질 전환 벡터인 pAR35-2를 개발하였다. 이 벡터를 Agrobacterium tumefaciens LBA4404에 형질전환 시킨 다음, 토마토와 담배 잎사귀 조직에 감염시켜 식물체들을 kanamycin과 hygromycin이 함유된 배지위에서 배양하여 형질전환된 식물체들을 선발하였다. 형질 전환된 식물체들로부터 antisense AL1-gene 및 antisense RNA를 각각 PCR 및 RT-PCR를 이용한 southern hybridization 방법을 이용하여 증명하였고, 토마토 식물체의 공변세포쌍 내에 있는 엽록체 숫자가 여덟 개라는 것이 확인되어 형질 전환된 토마토 식물체가 2 배수체로서 정상적인 식물체라는 것을 증명하였다. 이러한 형질 전환 식물체는 앞으로 항 바이러스성 형질을 지니는 식물체들을 개발하는 데 많은 도움을 주리라 여겨 진다. 그리고, 본 연구에서 제조된 벡터 pAR35-2는 두 개의 항생제에서 동시 선발 할 수 있도록 되어 있고 promoter가 두 개로 되어 있어 형질 전환 식물체선발 및 유전자 발현 연구에 효과적으로 이용되어 질 수 있으리 라 여겨진다.